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Gregw · 12-17-2003, 02:59 PM

I just purchased a rebuilt 455 with Hypereutectic Sealed Power pistons and stock rods. I want to duplicate the 455 Car Craft Built with E-Heads and Comp XE-274 cam. This engine had 500hp and around 580ft lbs of torque. This engine peeks at 5200rpm. Will these pistons live at this level of performance with street and seldom strip use?

Gregw · 12-17-2003, 02:59 PM

I just purchased a rebuilt 455 with Hypereutectic Sealed Power pistons and stock rods. I want to duplicate the 455 Car Craft Built with E-Heads and Comp XE-274 cam. This engine had 500hp and around 580ft lbs of torque. This engine peeks at 5200rpm. Will these pistons live at this level of performance with street and seldom strip use?

Rob · 12-17-2003, 05:50 PM

Hyperutectic=Lame

But can survive. If something goes wrong double or triple the disaster with those brittle, don't spend no money on them break everything pistons.

-Rob

Gregw · 12-17-2003, 06:34 PM

I purchased the engine complete from tbolt engine rebuilders in Houston TX. It is a stock rebuild and has 6-X heads on it, standard crank and .030 overbore. Could I upgrade to .030 Forged Pistons and beter rods without having to mess with the finish or size on the bore?

SCOTT ESTERLE · 12-17-2003, 08:06 PM

We sell thousands of those pistons & rarely have a problem. The problems that we normally see are from people not gapping the top ring properly.

bigcountry · 12-17-2003, 09:05 PM

Interesting that I had a hypertuetic pistoned 428 in a 69 firebird that consistantly ran in the 11's. Still runs great after about 400+ runs on the strip and 10,000 miles on the street. Like Scott said, if you do not gap the rings properly, you will definitely have problems.

The light at the end of your tunnel is just a freight train coming your way - Metallica

ventura7211 · 12-17-2003, 09:06 PM

My friend ran KB's in his sbc the past two seasons. The first season he broke two pistons and destroyed the block in the process. He bought a different block and a new set of KB's. At the last race this year his car started ticking the same way as it did last year. Turns out he broke two pistons again along with destroying another block. Something to think about.

But then for every guy who has had bad luck with them there are those who swear by them.

"Will these pistons live at this level of performance with street and seldom strip use? "

Probably.

Rob · 12-17-2003, 09:20 PM

If you build it cheap enough they will buy it.

I'm a little more demanding and would rather have happy come back customers, there's more than enough work for everyone. SRP Pistons good deal you will have to re-hone for .035 over. Free advice from a pro, just remember those 455s are getting harder to find. Lose the stock rods too.

-Rob

Gregw · 12-17-2003, 10:02 PM

Thanks for the input guys. My car has been parked since 1985 and when I finish putting it back together I would like to drive it and race it for a while without destroying anything. I had a 400 in it before and I am looking forward to feeling that 455 torque. I am hopeing it will run mid 7's in the 1/8 mile. My buddies Camaro runs 7.50's and rides the trailer to the track. I would like to drive down with the A/C on and run with him. He has been giving me a hard time about getting it running for 10 years!!

Rob · 12-17-2003, 10:43 PM

You're plenty welcome 500hp 580tq heavy street car with stock street setup I'd say 7.50 to 7.70 range. There's tires/chassis/tons of variables. Fairly big cam and it will probably go square 580hp-580tq good car and your looking at six's.

-Rob

Ron Landis · 12-18-2003, 09:19 AM

What Scott said...only two comlaints about "junk" KB pistons. Both on spray, my first question; "Did you set it up for spray?", met with a resounding "huh?" both times. GM feels comfortable putting them in all of their LT-1 and LS-1 motors and warranties them. Do it right...you'll be fine.

SCOTT ESTERLE · 12-18-2003, 09:33 AM

Now there Cheap pistons. They cost the same as Trw pistons. So what your saying is the Trw pistons are junk also. For a Street & Strip motor you would have no problems running KB'S OR TRW'S. As long as the motor is set-up properly. If your building a seriouse motor step up to some Wiseco's,JE'S,ROSS, OR SRP pistons.

Ken -Ace- Brewer · 12-20-2003, 07:50 AM

Like Scott said! We have sold hundreds here at PPR! I have dynoed over 2 dozen! Not one problem. Perfect street/strip piston!
Heck they even make over 500 hp on my dyno!
But to each his own!
Be Cool,
Ace

ACE-P.P.R.

Ron Landis · 12-20-2003, 09:53 AM

Scott, I was not calling the pistons junk, just paraphrasing what the customers have said, as I use them myself along with TRWs. I cannot afford $700 bucks a pop for slugs. My point being, many more failures can be attributed to poor assembly than to inferior products. Sorry if I was unclear in that respect. Anyway, I somehow missed you a Norwalk. We broke an axle as soon as we pulled to the line on track rental day and had to go back to Columbus for repairs. Got back the same night, but things were pretty hectic from then on out. Hotel mix ups and what-not. Anyway, hope you had as much fun as we did and look forward to seeing you there next year. BTW, your car looks sweet!

SCOTT ESTERLE · 12-20-2003, 11:01 AM

Thanks Ron. I wasn't talking about your comment. I was refferencing what Rob said about them. I understood what you were saying. Yes i had a good time.

Tim Corcoran · 12-20-2003, 11:30 AM

I think forged pistons are way over used. For some reason people think the first thing you have to do when you start a rebuild is get TRW forged pistons. The factory used cast pistons almost exclusively until recent years. Cast pistons are better than a forged piston for a street car. A cast piston is more stable with regards to thermal expansion than a forged piston. The cast piston will run quieter due to reduced piston rock and the ring seal will last longer due to a closer piston to cylinder wall clearance. A cast piston is lighter than a TRW forged piston and will be easier on the crank and rods and will make more power considering the rest of the combo being equal. A cast piston in most street strip machines will run trouble free for many years and would be a better choice than a forged piston. A factory replacement cast piston will work just fine in most street strip applications. The hypereutectic piston was developed to increase the strength of the standard cast pistons and still run a tight clearance. Basically the hypereutectic process involves adding more silicon to the alloy material and the casting process is changed some what. This makes the thermal stability even better and the piston is harder which makes them more resistant to wear and scuff. One of the properties of the hypereutectic piston is they retain more heat in the top of the piston than a standard cast piston. This is the reason that the top ring gap is critical for this type of piston. This is actually good from a power out put view point as retaining the heat you make more power. You will have a problem with any piston if you gap the rings too tight. Beck Racing Engines here in Phoenix use the KB Hypereutectic pistons in all their high performance crate engines up to 500 HP and they guarantee their engines too. The Big three are now using the Hypereutectic piston in their factory production vehicles more and more. I have seen these cars work fine with small amounts of boost and N20. Now with that said the cast pistons do have their limitations. I do not recommend using a standard cast or hypereutectic cast piston in a forced induction or N20 application. Also if you plan on making over 500 HP and plan to do regular racing then step up to a forged piston. The aluminum alloys and forging processes have improved over the years to reduce thermal expansion and attain a closer piston to wall clearance, but they still require about twice the clearance of a cast piston. For forced induction, N20, or naturally aspirated high power machines you need a forged piston as the cast pistons do have their limitations. My main point is, in many applications it is a waste of money to use a forged piston in a street machine when a cast piston will do a better job and last longer.

Tim C

65 LeMans, 3550lb. D-ports and a flat tappet cam, 10.90@121

Rob · 12-20-2003, 01:56 PM

Sorry didn't know that third sentence was for me.

Yes. 500hp/580tq isn't a job for the TRW either.

-Rob

Ron Landis · 12-20-2003, 07:55 PM

It seems that 500hp is the magic #, as that is what KB states in there tech section of their catalog that their pistons are tested to. Not recommending that, mind you, but that article, titled "nitrous...naughty but nice..", is pretty enlightening. I foolishly installed TRW forged in my first major Pontiac rebuild, having come directly from BBC engines. Seemed like a logical choice at the time. I later learned of the shortcomings of the poncho rod bolts, realizing that I had unintentionally made their task more daunting. Anyway, that motor is still hanging in there, even after several "rod checks". Attention to detail is the key, I believe.

Tim Corcoran · 12-20-2003, 08:05 PM

Rob

My post was just an opinnion on the subject. It was not directed towards anyone. You did bring up a valid point to consider. I agree that hyperutectic pistons are more brittle than standard cast or forged pistons, and in the event of failure could cause more damage to other parts.

Tim C

65 LeMans, 3550lb. D-ports and a flat tappet cam, 10.90@121

Rob · 12-20-2003, 08:37 PM

Whole thread seems reasonable to me. With all the CNC piston lathes now a days, you'd think someone besides JE-SRP would stock some reasonably priced performance pistons for Pontiac. I ask JE every year to make some more stocking sizes for Pontiacs and they still say there's no market. Diamond was a pain, have to harass wiesco some. TRW and KB know how easy the money is.

-Rob

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